Problem - Kevin Tafuro

to key data. In general, CALG_RC4 should work fine for arbitrary key data (the value
will effectively be ignored).
#include
#include
#include
void SpcIncrementalHMAC(BYTE *pbKey, DWORD cbKey, ALG_ID Algid) {
BYTE out[20];
DWORD cbData = sizeof(out), i;
HCRYPTKEY hKey;
HMAC_INFO HMACInfo;
HCRYPTHASH hHash;
HCRYPTPROV hProvider;
hProvider = SpcGetExportableContext( );
hKey = SpcImportKeyData(hProvider, Algid, pbKey, cbKey);
CryptCreateHash(hProvider, CALG_HMAC, hKey, 0, &hHash);
HMACInfo.HashAlgid = CALG_SHA1;
HMACInfo.pbInnerString = HMACInfo.pbOuterString = 0;
HMACInfo.cbInnerString = HMACInfo.cbOuterString = 0;
CryptSetHashParam(hHash, HP_HMAC_INFO, (BYTE *)&HMACInfo, 0);
CryptHashData(hHash, (BYTE *)"fred", 4, 0);
CryptGetHashParam(hHash, HP_HASHVAL, out, &cbData, 0);
for (i = 0; i < cbData; i++) printf("%02x", out[i]);
printf("\n");
CryptDestroyHash(hHash);
CryptDestroyKey(hKey);
CryptReleaseContext(hProvider, 0);
}
If you aren’t using OpenSSLor CryptoAPI, but you have a hash function that you’d
like to use with HMAC, you can use the following HMAC implementation:
#include
#include
typedef struct {
DGST_CTX mdctx;
unsigned char inner[DGST_BLK_SZ];
unsigned char outer[DGST_BLK_SZ];
} SPC_HMAC_CTX;
void SPC_HMAC_Init(SPC_HMAC_CTX *ctx, unsigned char *key, size_t klen) {
int i;
unsigned char dk[DGST_OUT_SZ];
DGST_Init(&(ctx->mdctx));
memset(ctx->inner, 0x36, DGST_BLK_SZ);
memset(ctx->outer, 0x5c, DGST_BLK_SZ);
278 | Chapter 6: Hashes and Message Authentication
This is the Title of the Book, eMatter Edition
Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.